Rational design of a cobalt sulfide/bismuth sulfide S-scheme heterojunction for efficient photocatalytic hydrogen evolution.

Following a simple one-pot hydrothermal method, a CoS/BiS composite was successfully synthesized using peanut-like BiVO as a precursor. After hydrothermal sulfuration, BiVO was transformed into BiS while maintaining its original peanut-like structure. Meanwhile, CoS nanoparticles were successfully coated onto the peanut-shaped surface of BiS, forming an S-scheme heterojunction by in situ hydrothermal method. For the growth system of CoS, the special three-dimensional (3D) structure of BiS provides a good growth site for zero-dimensional (0D) CoS nanoparticles, avoiding their aggregation and exposing, more reaction area of CoS. Moreover, the S-scheme heterojunction retains a more effective redox potential for this system and promotes the recombination of nonessential electron-hole pairs. The 0D/3D spatial structure and the construction of the S-scheme heterojunction provide a more efficient and convenient path for the transfer of photogenic charge, which greatly promotes the effective separation and diversion of the electrons. Besides, the cladding structure of the composite and the S-scheme heterojunction formed between BiS and CoS complement each other for jointly improving the hydrogen production performance of CoS/BiS.